The present application relates, in general, to electronics, and more particularly, to methods of forming packaging structure for semiconductor devices.
The semiconductor industry typically utilizes various methods and structures to form packages that encapsulate a semiconductor die and provide leads for electrically connecting to the semiconductor die. In one type of semiconductor package, the semiconductor die is mounted between a lead frame and a clip. The lower lead frame has a continuous flat surface on which the die is mounted then a clip is used to complete the electrical circuit on the top of the die. This configuration may provide inaccurate positioning of the semiconductor die to the lower lead frame. In addition, the same inaccurate positioning can occur with the clip. During mounting of both the die and clip, solder paste is typically used between the die to lead frame and clip to die. During reflow, both the die and clip may move, drift, tilt, and/or rotate, which can lower the quality and performance of the semiconductor device.
Accordingly, it is desirable to have techniques for mounting a semiconductor die that can reduce or eliminate drifting, tilting, or rotation. It is also desirable to have techniques for mounting different semiconductor dies using the same lead frame design.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, or certain N-type of P-type doped regions, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action. The use of the word approximately or substantially means that a value of element has a parameter that is expected to be very close to a stated value or position. However, as is well known in the art there are always minor variances that prevent the values or positions from being exactly as stated. It is well established in the art that variances of up to about ten percent (10%) (and up to twenty per cent (20%) for semiconductor doping concentrations) are regarded as reasonable variances from the ideal goal of exactly as described. For clarity of the drawings, doped regions of device structures are illustrated as having generally straight line edges and precise angular corners. However, those skilled in the art understand that due to the diffusion and activation of dopants the edges of doped regions generally may not be straight lines and the corners may not be precise angles.